Average Follow-up Time DetailThe baseline examination occurred between 1994 and 1995, while the follow-up evaluation occurred between 1997 and 1998.

"3,658 (73.6%) participants completed the follow-up evaluation...in the final cohort, we also included 231 (37.1%) of the 620 deceased participants who had adequate medical records...the final cohort of 3,824 participants consisted of 3,208 participants who screened negative [at follow-up] for dementia, 385 who screened positive [at follow-up] and who were either examined or had adequate medical records, and 231 deceased participants [at follow-up]with adequate medical records."

Exposure Detail"At baseline, all participants were asked whether or not they had a history of hypertension (diagnosed by their doctor) at any time during their life. If their response was affirmative, they were asked whether or not they were under treatment, the specific type of treatment (drugs, diet, other general measures), and the duration of hypertension and therapy...In this study, we considered a person as hypertensive if he/she answered positively to the hypertension question or if he/she had taken any pharmacological drug for hypertension."

Ethnicity Detail"The NEDICES study went into a well-defined area of central Spain and sampled three geographic areas...which represent the broad spectrum of Spanish societies..Las Margaritas, a working class neighborhood in Getafe (Greater Madrid); Lista, a professional-class neighborhood in Salamanca district (Central Madrid); and Arevalo, the agricultural region of Arevalo county (125 km northwest of Madrid)."

Age DetailEntry criteria required all participants to be age 65 or older at study entry.

"The diagnosis of dementia at baseline or during follow-up was made by the consensus of two neurologists, who were blinded to hypertension status, and was based on the neurological assessment and examination. The medical records of all participants who received a diagnosis of dementia were reviewed by a senior neurologist (F.B.P.) with the aid of a psychologist. If there were doubts about any aspect of the dementia diagnosis, additional information (mainly from family doctors) was elicited."

"Person-years for participants who did not develop dementia were calculated as the time between the baseline screening and the screening for the follow-up survey or death. Conversely, person-years for participants who developed dementia were calculated as the time between the baseline screening and the reported onset of cognitive complaints. If the onset of cognitive complaints was unknown, person-years were calculated as the midpoint between the baseline screening and the follow-up screening or death."

The reported associations adjust for several factors that may mediate the relationship between blood pressure and Alzheimer disease. Unadjusted and partially adjusted models yield effect sizes of similar direction and magnitude.